data: saving typedef to Storage

This change save typedef expressions to the Storage using a node of type Node::NODE_TYPEDEF and an edge of type
Edge::EDGE_TYPEDEF_OF that leads to the original type, with the qualifiers saved as DataType on the edge.

src/lib/data/graph/Node.cpp

@@ -266,6 +266,8 @@ std::string Node::getTypeString(NodeType type) const
 		return "namespace";
 	case NODE_ENUM:
 		return "enum";
+	case NODE_TYPEDEF:
+		return "typedef";
 	}
 	return "";
 }